First, make the filling. Heat a splash of oil in a saucepan and add the diced onions. Cook gently for 15 - 20 minutes, stirring occasionally so they don't burn. Once they have softened, add the honey and vinegar and mix thoroughly. Add the garlic, cumin and chilli flakes, and continue to cook on a low heat for another 5-10 minutes, stirring from time to time.
Heat the oven to 180deg C. Rinse, drain and pat dry the chickpeas (a sheet of kitchen roll will do). Toss them in about 1 tbs olive oil & 1/2 tsp salt. Don't add too much oil or the chickpeas will end up swimming in it and soggy.
Roast them in a baking tray for 20 to 30 mins, shake & turn the tray every 10 mins. Some may pop, it’s ok. They are done when golden & slightly darkened, dry and crispy on the outside, soft on the inside.
Remove from heat and add the sumac.
Spread the walnuts on a baking tray, roast for 5 mins. Toss together the hot walnuts, butter, smoked paprika and a large pinch of salt in a bowl, then tip them back onto the baking tray. Roast for 2-3 more mins to dry the coating.
Steam the broccoli until tender.
In a large bowl combine all the cooked ingredients with the cheese. Check the seasoning. Leave the filling in the fridge to chill for half an hour.
Roll out your shortcrust pastry to about 2-3mm thickness. Cut into circles of approx. 12cm diameter. (If you want to go the extra mile, it's worth making your own sour cream pastry for the empanadas. It's such a buttery, flaky, delicious pastry, and a perfect match for this filling.)
To make up the empanadas, put a dessert spoon of filling into the centre of each pastry circle. Fold the pastry over the filling to create a semicircle and press the pastry circle edges together. You can do this with your fingers, or with a fork. In Argentina the edges are folded over to create a pretty border, but it's not necessary.
Pop the empanadas onto a baking tray and brush them with egg or milk. Cook them for 20-25 minutes.